The New Atlantis has a nice piece, The Global War Against Baby Girls. It’s relatively heavy on charts and maps, so I recommend it (yes, it has a particular ideological perspective, but that’s really not consequential, as I assume most readers do not favor skewed sex ratios either). There’s nothing too surprising in it (assuming you won’t be surprised by the finding that in many societies there is a correlation between economic development and higher rates of sex selective abortion). But it’s thorough and highlights the complexities of social dynamics well.

The author notes that Gary Becker and Judge Richard Posner hypothesized that a sex imbalance should lead to an increase in the status and value of women. This is a classic expectation that systems go back to equilibrium, and dovetails well with what we know from biology, where sex ratios tend to cycle in a meta-stable manner around balance in many species. But the empirical reality is a little more murky. Instead of a rise in the “status” of women there have been regions of China where women are further commoditized, and turned into an item for purchase and sale. This is probably not what Becker and Posner had in mind, though it might follow the letter of their prediction if not the spirit. Additionally, social systems are complex enough that they may take a tortuous and circuitous route back toward equilibrium.

I will also add two points, one minor, and one not as minor. The author suggests that Vietnam is not a Confucian society, but a Buddhist one. This is somewhat misleading. Though not nearly as Confucian as Korea, Vietnamese high culture did mimic aspects of Chinese state ideology to some extent, including introducing a Confucian scholar-administrative element. Vietnam is arguably more Sinic than Japan, having been under Chinese rule, and being directly tributary, for much of its history. A bigger point is that sex imbalance ratios are a matter of class and globalization. As hundreds of millions of lower class Chinese men reach maturity without the means to enter into a monogamous relationship with Chinese women, they will do what marginalized South Korean men have been doing: look to Southeast Asia. This means that Southeast Asian men without means will themselves be lacking in partners. A similar phenomenon has occurred in India, where women from eastern states have migrated to Punjab to marry men who can not find partners in the local region. One can not understand the sex imbalance story without considering its entailment: the great migration of tens of millions of women from poor societies to the the lower rungs of wealthier societies.